Pump structure



Dec. 9, 1941.

IIIIIIIIIIII.

J.. F. HoFFER 2,265,232

PUMP STRUCTURE Filed May '7, 41938 2 Sheets-Sheet 1 Patented Dec. 9, 1941 UNITED PUMP STRUCTURE James F. Hoier, Detroit, Mich., assignor to Ex- Cell-O Corporation, Detroit, Mich., a corporation of Michigan Application May 7, 1938, Serial No. 206,509

8 Claims.

The present invention relates to improvements in pumps, and has particular reference to a new and improved pump which is especially suited for supplying fuel at a relatively low pressure to a second pump adapted to deliver fuel in metered charges at a relatively high pressure to an internal combustion engine.

One of the objects of the invention is to provide a novel pump which will deliver fuel at a relatively constant pressure but in a varying amount in accordance with the demands placed upon it.

Another object is to provide a new and improved pump of the foregoing character which is power operated and which has a pressure responsive discharge plunger adapted to be manually operated independently of the power drive to deliver fuel for priming purposes.

A general `object is to provide a new and improved pump of the foregoing character which is simple and compact in construction and which is eicient and reliable in operation.

Other objects and advantages will become apparent as the description proceeds.

In the accompanying drawings,

Figure 1 is a side elevational view partially in longitudinal section of a pump structure embodying the features of my invention.

Fig. 2 is a fragmentary transverse sectional view taken 4along line 2--2 of Fig. 1.

Fig. 3 is a fragmentary transverse sectional view taken along line 3-3 of Fig. 1.

Fig. 4 is an enlarged fragmentary sectional view of the auxiliary leakage pump.

Referring more particularly to the drawings, the pump structure illustrating the invention comprises generally a delivery pump I for discharging iluid under a relatively high pressure, and a primary pump 2 for supplying or transferring fluid under a relatively low pressure to the inlet of the delivery pump. The primary pump 2 serves also to return fluid leaking from the delivery pump to the inlet of the latter, and for this purpose preferably includes an auxiliary pump 3 for introducing the leakage uid into the primary pump for mixture and delivery with the normal uid supply. The present application is directed to the primary pump 2. The auxiliary pump 3 and various combinations of the pumps I, 2 and 3 are covered in my copending divisional application Serial No. 344,343, led July 8, 1940.

The high pressure delivery pump I may be of any desired form or type, and is herein disclosed for purposes of illustration as an adjustable metering and distributing fuel pump like that disclosed in a copending application by Carroll R. Alden, Serial No. 124,220, filed February, 1937 (Patent No. 2,156,933) Briefly described, the delivery pump I comprises a housing 4 adapted to be mounted on a suitable support. A cylinder body 5 is mounted in one end of the housing 4, and is formed with a central bore 6 and with a plurality of parallel pump cylinders 'I arranged in annularly spaced relation about the bore. A plurality of pump pistons 8 are reciprocably disposed in the cylinders I and are urged outward ly by compression springs 9. Mounted in the other end of the housing 4 is a driving mechanism for effecting reciprocation of the pistons 8 in uniformly timed sequence. This mechanism comprises a plurality of actuating plungers II reciprocably guided in the housing 4, and disposed in axial alignment and end abutting engagement respectively with the pistons 8. A rotary swash plate I2 coacts with the plungers II, and is operable by a central drive shaft I3 in axial alignment with the bore 6. The pressure ends of the pump cylinders 1 open respectively past check valves I4 to a plurality of delivery lines I5, and have individual inlet ports I6 opening in a common transverse plane to the bore 6. A groove I1 is formed in the periphery of the bore 6, and is open to an inlet passage I8 connected to a low pressure uid supply line I9. Mounted in the bore 6 is a rotary valve member 20 having a relief area 2I adapted to effect communication be tween the ports IS and the groove II and having a narrow land area 22 movable successively across the ports to close each port during a predetermined portion of the working stroke of the associated piston 8. The valve member 20 is operatively connected to the shaft I3 for rotation thereby in timed relation to the reciprocation of the pistons 8.

In operation, predetermined quantities of fluid, such as liquid fuel, are discharged under a relatively high pressure and in timed sequence to the delivery lines I5. Any fluid leaking from the closed ends of the cylinders I along the pistons 8 or from the groove I 'I inwardly along the valve member 20 will pass into the interior of the housing 4 between the cylinder body 5 and the driving mechanism.

The primary pump 2 comprises a body 23 located withir and integral with the bottom wall of a. casing 24 which is open at the top and bolted to the underside of the pump housing 4. The interior of the casing 24 is open to the pump housing 4, and adapted to receive and collect any fluid leaking into the latter from the pump body 5.

The body 23 is formed with a longitudinal pump cylinder 25 open at opposite ends to the interior of the casing 24. A guide bore 26 in spaced axial alignment with the cylinder 25 opens through one end wall 21 of the casing 24, and is closed at the outer end by an end plate 28 suitably bolted in position.

Formed in the cylinder 25 intermediate its ends is a peripheral groove 29 connected at opposite sides respectively through inlet and outlet valves 39 and 3| to supply and delivery passages 32 and 33. The inlet valve 30 comprises a bore defining a valve chamber 34 opening downwardly in one side of the body 23 and connected through a passage 35 to the groove 29. A valve passage 36 intersects the supply passage 32 and opens through an annular valve seat 31 to the chamber 34. A suitable valve member 38 is slidably guided in a screw cap 39 threaded with a fluid tight seal into the upper end of the chamber 34, and is normally urged by a compression spring 40 into engagement with the seat 31. The passage 32 opens to one end of the casing 24, and is connected through a screw tting 4| to a conduit 42 adapted for connection with a suitable source of fluid supply, such as a tank (not shown). It will be understood that the valve 39 will open in response to the intake pressure in the cylinder 25.

The outlet valve 3| comprises a bore dening a valve chamber 43 in the other side of the body 23, and closed at the outer end by a screw cap 44. The chamber 43 intersects the delivery passage 33, and is connected to the groove 29 through a valve passage 45 encircled by an annular valve seat 46. A valve member 41 is slidably guided in the cap 44, and is normally urged into engagement with the seat 46 by a compression spring 48. It will be understood that the valve 3| will open in response to the delivery pressure in the cylinder 25. The passage 33 opens to one end of the casing 23, and is connected through a screw fitting 49 to the line or conduit I9 leading to the inlet of the pump I.

The pump 2 also comprises a piston having a head 59 and a cup-shaped guide 5| interconnected by an axial stem 52, and reciprocable respectively in one end of the cylinder 25 and in the guide bore 26. Suitable openings 53 are formed in the connecting end wall of the guide I to permit pressure relief in the bore 26. Preferably, the piston 59 is driven by the pump I and hence in timed relation to the pistons 8. The drive comprises a rocker lever 54 mounted intermediate its ends on a pin 55 in'thecasing 24 for oscillation about an axis extending transversely of the piston 59. The upper end of the lever 54 is rounded, and engages in a transverse notch 56 in the underside of the lowermost operating plunger II. The lower end of the lever 54 is similarly rounded, and engages in an annular groove 51 defined by the piston head 59 and a spaced ange 58 integral with the stem 52.

Extending reciprocably into the end of the cylinder 25 opposite the piston 59 is a pressure control plunger 59. This plunger is urged inwardly by spring pressure, and in effect constitutes a yieldable end wall for the pressure chamber of the pump 2. Inward movement of the plunger 59 is limited by a stop 69 adjustably mounted within the casing 24. In the present instance, the stop 69 consists of a disk which projects peripherally into an annular groove 6I formed in the outer end of the plunger 59 and dening oppositely facing abutment shoulders 62 and 63. The stop 69 is slidably mounted on the inner end of a rod 64 extending slidably through the pump body 23 and the end wall 21 and end plate 28 to the exterior of the casing 24 in parallel relation to the plunger 59, and is normally in engagement with the adjacent end of the pump body. A priming lever 65 is pivotally mounted on a bracket 66 on the end plate 28, and is provided with a lug 61 in abutment with the outer end of the rod 64. The lever 65 is normally held in its outermost position by means of a spring 68. It will be evident that swinging the lever 65 inwardly against the rod 64 will cause the stop 69 through engagement with the shoulder 62 to shift the pressure plunger 59 outwardly in a pump priming stroke.

Any suitable spring means may be provided for urging the plunger 59 inwardly. In the present instance, the plunger 59 is formed with an' axial bore 69 opening to the outer end. A oat bushing 19, having an internal flange 1| defining a spring seat, is slidable in the bore 69. A compression spring 'I2 in the bore 69 engages one side of the seat 1|. A similar spring 13 engages the other side of the seat 1I and a stationary seat 14 mounted in the adjacent end wall of the casing 24. The bushing 19 permits the use of the two relatively short springs 12 and 13 which will not tend to buckle objectionably or rub against the surface of the bore 69 as would be likely if a single long spring were employed in their stead. A third compression spring 15, encircling the spring 13 and also engaging the seat 14, acts directly against the outer end of the plunger 59. The three springs 12, 13 and 15 all tend to urge the plunger 59 inwardly, and are provided in lieu of one spring in order to obtain the desired thrust force and at the same time avoid a high spring rate. By the present construction, no perceptible or material variation in the thrust force over the range of spring movement is experienced, and consequently the plunger 59 tends to maintain the delivery of the pump 2 under a substantiallyv constant pressure regardless of volume displacement.

In operation, fluid will enter the cylinder 25 through the valve 39 'during the suction stroke of the piston 59, and will be discharged through th'e valve 3| during the pressure stroke. The pressure plunger 59 is operable automatically to vary the displacement of the pump 2 in accordance vwith the requirements of the pump I at a predetermined maximum pressure. If the maximum displacement of the pump 2 is required, the springs 12, 13 and 15 will hold the shoulder 62 in engagement with the stop 69 to locate th'e pressure plunger 59 in its innermost position. In the event that the full displacement of the pump 2 is not required, the pressure in the cylinder 25 will cause the plunger 59 to move outwardly during vthe pressure stroke of the piston 59 so that only part of the displacement of the piston will be discharged through the valve 3|. In the subsequent suction stroke, th'e plunger 59 will move inwardly to maintain the fluid in the cylinder 25u11- der the predetermined maximum discharge pressure. until the shoulder 62 again engages the stop 69, and thereafter fluid in an amount sufcient to rell the cylinder 25 will enter through the valve 39. It will therefore be evident that the pump is self-relieving.

The function of the hand lever 65 and associated parts is to permit manual reciprocation of the plunger 59 independently of the piston 59 for the purpose of priming the injection system without rcranking the engine. Hand priming is resorted to when for any reason the system becomes air bound, for example, as a result of the fuel tank running dry. The priming is accomplished by working the lever 65 a suflicient number of full strokes to expel the air and to iill the system with oil under maximum primary pump pressure. Thereafter, the springs 12, 13 and 15 will fail to move the plunger 59 to the left, thereby automatically rendering the hand priming mechanism inoperative as soon as its purpose is accomplished.

The primary pump 2 serves to return leakage fluid collecting in the interior of the casing 24 to the inlet of the pump l. The auxiliary pump 3 is automatically operable to return the leakage fluid into the cylinder during the suction stroke of the piston 50. In its preferred form, the pump 3 is built into the piston 50, and specifically comprises an axial cylinder bore 16 opening through the stern 52 and having radial inlet ports 11 opening to the groove 51. The inner end of the bore 16 is adapted to discharge through an outlet valve 18 into the cylinder 25. A pump plunger 19 is reciprocable in the outer end of th'e bore 16, and is provided with an external head 80 normally held against the end plate 28 by a coiled compression spring 8|.

During the pressure stroke of the piston 50, the plunger 19 is relatively retracted from the bore 16 to uncover the ports 11. If the fluid level in the casing 24 is at or above the ports 11, the fluid will enter and fill th'e pressure end of the bore 16. During the subsequent intake stroke of the piston 50, the plunger 19 will be forced into the bore 16 in a pressure stroke to discharge the fluid past the valve 18. The capacity of the pump 3 is sufciently in excess of the .normal leakage that the uid level in the casing 24 will be automatically maintained at the ports 11.

The leakage pump plunger 19 is formed with a peripheral groove 82 which is connected through radial bores 83 and an axial bore 84 to the inner end of the plunger, and which is movable into registration with the inlet ports 11 at the end of the pressure stroke to relieve the pressure in the cylinder bore 16. The relief or by-pass determines the end point of pressure discharge by the plunger 19. Consequently, changes in the length of stroke of the piston as would be obtained by substitution of swash plates l2 of different angularities, will not change the eective capacity of the pump 3. The effective portion of the pressure stroke of the plunger 19 will remain constant regardless of changes in the length of relative plunger travel. If the level of leakage fluid in the casing 24 is below the ports 11, the cylinder bore 16 will be charged with air. The relief or by-pass also serves to prevent excess movement of the plunger 19 from compressing the air to a pressure sufiiciently high to open the valve 18.

The valve 18 comprises a hollow body 85 threaded into an axial bore 86 in working end of the piston 50 and connecting with the cylinder bore 16. A tapered member 81 is rigidly secured in the inner end of the body 85, and is clamped against the inner end edge of the bore 16 to define in effect the end wall of the latter. The member 81 is formed with a restricted valve port B8 opening from the bore 16 through a relatively large valve seat 89 to the interior of body 85. A ball valve member 90 is normally urged into engagement with the seat 89 by a retainer 9| actuated by a coil compression spring 92. 'Ihe pressure of the spring 92 is suiiiciently high to prevent opening of the valve 18 by air pressure or air-liquid emulsion pressure within the cylinder bore 16. The restriction of the port 88 prevents large particles of dirt and other foreign matter from entering the valve 18 and interfering with seating of the valve member 98. In the event that the valve member 90 fails to seat, th'e restriction also serves to insure continued delivery of uid by the pump 2 so that when the pump structure is employed to supply fuel to an engine the latter will not stop for lack of fuel.

I claim as my invention:

1. A pump comprising, in combination, a body having a pump cylinder, a piston reciprocable in said cylinder, means for supplying iiuid to said cylinder during the outward stroke of said piston and for discharging fluid from said cylinder during the reverse stroke of said piston, a pressure control plunger reciprocable in said cylinder independently of said piston and constituting an end wall thereof in opposed relation to said piston, said control plunger being movable outwardly solely in response to fluid pressure in said cylinder, and spring means tending to urge said plunger inwardly with a predetermined pressure.

2. A pump comprising, in combination, a casing having a body with a pump cylinder, a pump piston reciprocable in one end of said cylinder, a passage including an inlet check valve for supplying fluid to said cylinder, a passage including an outlet check valve for discharging fiuid from said cylinder, a plunger reciprocable in the other end of said cylinder in opposed relation to said piston and projecting from said cylinder, adjustable means having a lost motion connection with the outer end of said plunger, a stop adapted for engagement by said means for limiting the inward movement of said plunger, and spring means tending to urge said plunger inwardly, said adjustable means being operable to move said plunger outwardly against the action of said spring means.

3. A pump comprising, in combination, a casing having a body with a pump cylinder and an axially aligned guide bore, a pump piston reciprocable in said bore and in one end of said cylinder, a passage including an inlet check valve for supplying fiuid to said cylinder, a passage including a check valve for discharging fluid from said cylinder, a plunger reciprocable in the other end of said cylinder in opposed relation to said piston, a groove in the outer end of said plunger, a stop projecting into said groove for limiting the range of movement of said plunger, and spring means tending to urge said plunger inwardly with a predetermined pressure.

4. A pump comprising, in combination, a body having a cylinder bore open at both ends, a plunger reciprocable in one end of said bore and formed with an external peripheral groove, a coil compression spring acting against the outer end of said plunger, and tending to urge said plunger inwardly, a stop dog mounted on said body for adjustment longitudinally of said plunger and projecting into said groove to limit the movement of said plunger in one direction, said stop dog being normally in positive stop engagement with said body to limit inward movement of said plunger, a pump piston reciprocable in the other end of said pump cylinder, and means for supplying fluid to said cylinder bore and for discharging fluid from said cylinder bore in response to the action of said plunger and said piston.

5. A pump comprising, in combination, a body having a cylinder bore open at both ends, a plunger reciprocable in one end of said bore and formed with an external peripheral groove and with an axial guide bore open to the outer end, a coil compression spring disposed in said plunger and seated against the inner end of said guide bore, a floating bushing slidable in said guide bore and seated at one side against the outer end of said spring, a second coil compression spring in axial alignment with said rst mentioned spring and acting against the other side of said bushing, said springs tending tol urge said plunger inwardly, a stop dog mounted on said body and projecting into said groove to limit the movement of said plunger in one direction, a pump piston reciprocable in the other end of said pump cylinder, and means for supplying iluid to said cylinder bore and for discharging fluid under pressure from said cylinder bore in response to the action of said plunger and said piston.

6. A pump comprising, in combination, a body having a cylinder bore open at both ends, a plunger reciprocable in one end of said bore and formed with an external peripheral groove and with an axial guide bore open to the outer end, a coil compression spring disposed in said plunger and seated against the inner end of said guide bore, a oating bushing slidable in said guide bore and seated at one side against the outer end of said spring, a second coil compression spring in axial alignment with said first mentioned spring acting against the other side of said bushing, a third coil compression spring encircling said last mentioned spring and acting against the outer end of said plunger, said three springs tending to urge said plunger inwardly with a predetermined pressure, a stop dog mounted on said body for adjustment longitudinally of said plunger and projecting into said groove to limit the movement of said plunger in an inward direction, a pump piston reciprocable in the other end of said pump cylinder, and means for supplying fluid to said cylinder bore and for discharging fluid under pressure from said cylinder bore in response to the action of said plunger and said piston.

7. A pump comprising, in combination, a body having a pump cylinder, a piston reciprocable in one end of said cylinder, means for supplying fluid to said cylinder during the outward stroke of said piston and for discharging uid from said cylinder during the inward stroke of said piston, a pressure control plunger reciprocable in the other end of said cylinder in opposed relation to said piston, said fluid supply and discharge means opening to said cylinder between said piston and said plunger, spring means tending to urge said plunger inwardly toward said piston, power driven means for reciprocating said piston, and manual meansfor effecting reciprocation of said plunger at will independently of said piston, whereby said piston or said plunger may be operated to pump uid.

8. A pump comprising, in combination, a body having a pump cylinder, a piston reciprocable in said cylinder, a plunger reciprocable in said cylinder in opposed end relation to said piston, power driven means for reciprocating said piston, means for limiting the inward movement of said plunger to juxtaposition to said piston when said piston is substantially at the end of its inward movement, spring means tending to urge said plunger inwardly and permitting outward movement of said plunger in response to a predetermined fluid pressure in said cylinder between said piston and said plunger, and means for admitting Huid to said cylinder between said piston and said plunger during the outward stroke of said piston and for discharging uid from said cylinder in response to th'e pressure of sai plunger.

JAMES F. HOFFER. 

